病例報告-同側同時診斷之後天性囊性腎病相關腎細胞癌和未分類腎細胞癌

張家郡、蕭博任

中國醫藥大學附設醫院 泌尿部

A Case report of Ipsilateral Synchronous Acquired Cystic Disease-Associated Renal Cell Carcinoma and Unclassified Renal cell Carcinoma

Jia-Jyun Jhang, Po-Jen Hsiao

Department of Urology, China Medical University Hospital, Taichung, Taiwan

Introduction: We present an acquired cystic kidney disease (ACKD) patient initially found with multiple lung lesions. Wedge resection of lung tumor revealed poorly differentiated carcinoma of unknown origin. Subsequently, the patient was diagnosed with two subtypes of Renal cell carcinoma (RCC) in the left kidney: acquired cystic disease-associated RCC and unclassified RCC. The latter was suspected to be the primary tumor of lung metastasis. Treatment with Tyrosine kinase inhibitor (TKI) was initiated, and partial response was observed during a 9-month follow-up period.

Case presentation: This 50-year-old male with end-stage renal disease (ESRD) status male is under hemodialysis for more than 20 years. He previously received laparoscopic anterior resection for sigmoid cancer. During follow up, a Positron Emission Tomography (PET) scan revealed suspicious lesions in both lungs. Wedge resection was performed revealing poorly differentiated carcinoma of unknown origin. Primary large cell carcinoma with lung-to-lung metastasis was suspected. However, CT done one month post operation showed diffuse new lung nodules prompting suspicion of an alternative tumor origin. A repeat PET scan indicated increased FDG uptake in the left kidney, raising suspicion of possible malignancy. Subsequently, left radical nephrectomy was performed and two subtypes of RCC was found: acquired cystic disease-associated RCC, and unclassified RCC with renal vein invasion and sarcomatoid features. Reviewing the histopathology, unclassified RCC was deemed the likely primary tumor responsible for the lung metastasis. TKI was prescribed and image series 9 months later showed partial response.

Discussion: ACKD patients have a 3-7% risk of developing RCC, which is 100 times higher than the general population. Two distinctive histological subtypes of RCC have been identified in ACKD patients: Acquired cystic disease–associated RCC and Clear cell papillary RCC. However, it's crucial to recognize that other subtypes of RCC may hide in the shadow of ACKD. Unclassified RCC represents a subgroup with heterogeneous histology that defies classification into recognized subtypes with a relatively poor prognosis. For advanced stage unclassified RCC, systemic therapy with TKI and immune checkpoint inhibitors (ICIs) is currently the standard choice of treatment. As demonstrated in our case, this approach may yield promising outcomes.